In the art of guns in which projectiles are projected by non-chemical means, the use of magnetic energy to launch projectiles is known. Such magnetic energy may be generated by the use of electromagnets or permanent magnets. Generally, in electromagnet guns, electromagnet coils are arranged with respect to a barrel in an array so that the axes of the coils are collinear or parallel to the axis of the barrel and thereby parallel to the direction of the projectile motion down the barrel. Two types of such prior art electromagnetic guns are known as plasma-armature railguns, or simply railguns, and coaxial induction guns.
Railguns are limited in their performance by barrel effects such as wall ablations. It would be desirable to provide an electromagnetic gun that is not plagued with deleterious wall ablation effects.
Coaxial induction launchers present problems to effective performance because their major magnetic forces are radial and non-accelerating rather than axial and in-line with the velocity of the projectile. Also, there is a substantial problem of ohmic heating of the armature with coaxial induction launchers. It would be desirable to provide an electromagnetic gun with minimum radial magnetic forces and maximum axial magnetic forces. Also, it would be desirable to provide an electromagnetic gun with minimal effects due to ohmic heating.
Railguns and coaxial induction guns are limited to the volume of the gun bore with regard to the volume of magnetic energy used for accelerating the projectile down the barrel. It would be desirable to provide an electromagnetic gun which can use a larger volume of accelerating magnetic energy.
There are a number of other electromagnetic guns in the prior art. In such guns, an arrangement of electromagnet coils is provided along the gun barrel with coil axes transverse to the direction of projectile motion. In one such gun, the transversely arrayed coils are arranged in opposing N-N or S-S orientation and are used to bring about spin in cylindrical projectiles in the barrel. Opposing magnetic polarities in electromagnets inherently consume more electric energy than complementary N-S and S-N arrangements. It would be desirable to provide an electromagnetic gun which employs complementary N-S or S-N electromagnets.
In another prior art electromagnetic gun which employs coils arranged transverse to the direction of projectile motion along the barrel, a pair of flat rails have a steady direct current flowing therethrough which is used to interact with the magnetic field across the coils to provide a net accelerating force on a flat projectile. It would be desirable to provide an electromagnetic gun which does not require additional rails to bring about acceleration of the projectile.
In general, with the prior art electromagnetic guns in which transversely arranged coils are used, the transversely arranged coils do not and cannot bring about an increase in projectile velocity through the barrel. The coils are actuated with current prior to arrival of the projectile and are maintained in an actuated state while the projectile passes the coils. In fact, permanent magnets could replace the electromagnets and provide a constant magnetic flux. As the projectile is propelled down the barrel, it experiences both deceleration and acceleration as the projectile enters and exits the gap between opposing coils. Thus, even though there are induced currents generated in the projectile as it moves down the barrel, the net acceleration effect due to those induced currents is zero because of the cancelling of deceleration and acceleration effects. It would be desirable if an electromagnetic gun did not have the inherently cancelling deceleration and acceleration effects upon a projectile having induced currents that moves down the barrel of the gun.
Another feature of prior art electromagnetic guns is the use of projectiles made from a magnetic material. Projectiles made from a magnetic material limit the magnetic pressure that can be applied. Therefore, when a magnetic projectile is used, high acceleration cannot be achieved. It would be desirable to provide an electromagnetic gun which employs a nonmagnetic projectile.